The present invention relates to an abduction-type motor such as drive motor for information devices, fan motor and disk drive motor and to a fabrication method of its motor stator.
Generally the fabrication of an abduction-type motor involves simple coil winding machine work in order to obtain high-density coil windings. However, recent requirements include coil winding with even higher density in order to downsize the motor and increase its efficiency. In order to meet this requirement, and to enable the stator structure to increase the occupied coil volume, a divided type stator is used which has its core divided into several parts, each corresponding to the individual poles and with the stator being fabricated after the coil winding work.
Japanese Patent Laid-Open Number 2000-152528 is an example of a prior art abduction-type motor with a divided stator core. In this method, the divided cores are linked together with thin magnetic material at the heads of the teeth parts of the individual divided cores, and the cores, which are die-cut in a rectilinear shape, are assembled in a circle after the coil winding work. Then, the single end part is fastened. In this example, the final step is completed by fastening the single end part by using the coupling pin, which may be fixed alternately by welding work.
Since the magnetic poles are connected by magnetic materials in the above prior art, magnetic flux leakage may occur between the magnetic poles and the efficiency of the motor may be significantly reduced. Though the machine-wound operation can be applied by machines for the individual divided cores at the coil winding work, the finishing work for the end part of the individual coil winding is required instead of finishing the end part of the entire continuous coil line. It is especially required to wind a set of coils for an identical phase at the divided cores separated away from one another in a multi-phase and multi-pole machine, and in this example, the finishing work for the coil winding is required for the individual divided core, which requires an extended period of time.
An example of the coil winding is shown in FIG. 2. In this example, the stator core 5 having 12 poles is shown, and in case of applying the coil winding work with the coil 7 for the single phase (corresponding to four poles) at the divided core, it is assumed is such a method, as shown in FIG. 2(a), that four poles are made supported in a circumferential direction by the support tool for the coil winding work, applied by the coil winding machine flyer 31. When the length of the crossover line is longer or shorter than the designated line length, this method can be only applied to the motor in which four coils are arranged uniformly at 90° positions. For example, as the coil arrangement for 10 poles and 12 slots is thus shown in FIG. 2(b), the excessive length arises at the crossover line between adjacent coils, and thus the insufficient length arises at the crossover line between coils with rotational symmetry. Thus, it is one of problems to be solved in coil winding to reduce the excessive and/or insufficient length of the crossover line.
In addition, when fabricating the divided cores, it is important to fabricate the divided cores so as to prevent the wound coils from interfering one another. In case of applying the coil winding method shown in FIG. 2(a), the line extended between the start point and the end point for the wound coil is located inside the inner diameter of the core. This is because the coil winding work is performed while the tension applied during the coil winding work is directed inside the inner diameter, which causes the irregular coil outline even if the start point and the end point of the coil are forced to be located in the direction toward the outside diameter, and ultimately the occupied volume of the coil is reduced.
An object of the present invention is to provide a high-efficiency and small abduction-type motor and a fabrication method of its motor stator whereby the stator core is divided, the coil winding work is applied to the divided cores with higher occupied volume, and the stator core, including the coil windings, is configured to be easily reassembled so that the finishing work for the end part of the individual coil winding may be eliminated and a continuous machine-wound is formed.
In order to solve the above problems, in an abduction-type motor having a divided core formed by dividing a stator core into plural blocks, and a motor stator having such a structure as the divided core may be reassembled, the motor has a coil arranged and is wound by supporting the divided core so that the teeth top parts of the divided core are directed inside and located on a circle, and the lead lines for the start of the coil winding and the end of the coil winding are arranged at the teeth top parts.
In the coil winding structure of the divided core, the number of coil stages, for the teeth top parts of the divided cores located outside, is made larger than the number of coil stages for the inside parts.
The diameter of the teeth top part of the divided core, after assembly, is identical to the diameter of the teeth top part of the divided core maintained during the coil winding work, and the finished coil winding is so formed as to have an adequate pressure extended length for a single slot.
The stator core has a coil winding frame formed as a series of units, each coupled at the coupling parts made of insulation material and embedded into the individual divided core, a part of which can be flexibly bent.
In the assembly method of the abduction-type motor having a divided core formed by dividing the stator core into plural blocks with its teeth top parts arranged in the direction to the outside and having such a structure as to be reassembled with said divided cores, the motor stator is assembled by means of a coil winding frame formed as a series of units. Each unit is coupled by coupling parts made of insulation material and embedded into the individual divided core, a part of which can be flexibly bent. The coupling parts of the coil winding frame are deformed and arranged during the coil winding work so that the teeth top parts of the divided core may be arranged on a hypothetical circle and directed to its inside. The coil winding work is applied continuously to the divided cores, and the coupling parts of the coil winding frame is deformed after the coil winding work, so that the teeth parts of the divided core may be directed to the outside.
According to the present invention, since the abduction-type motor is structured so that its stator core may be formed as a set of divided and coupled units, and its coupling part makes it possible to reassemble the divided units easily, it will be appreciated that a continuous machine-wound work can be realized without processing the cable terminals of the coil windings, and that a high-efficiency and small-sized abduction-type motor can be realized.
In addition, as the continuous coil winding work is enabled by directing the teeth top parts of the divided cores outside and arranging them on a hypothetical circle at the coil winding work, and the stator core is assembled by transforming the divided cores at the center of the engagement part of the coil winding frame after the coil winding work so that its teeth top parts may be directed inside, the length of the individual crossover lines between the divided cores when arranging the teeth top parts so as to be directed outside and located on the hypothetical circle at the coil winding work can be almost identical to the necessary length of the individual crossover lines after the assembly process, and thus, it will be appreciated that the terminal process for the coil cable at the assembly process can be eliminated.
As the teeth top parts of the divided cores are arranged inside and the number of coil stages for the teeth top parts of the divided cores (located outside) is made larger than the number of coil stages for their inside parts, which leads to the optimum arrangement of the crossover lines at the teeth top part, that is, the circumferential part of the cores assembled as the stator core, for the start of the coil winding and the end of the coil winding, it will be appreciated that the interference between the coils at the assembly process can be avoided.
In addition, as the continuous machine-wound work without any coil winding work can be realized, it will be appreciated that the structure for assembling the divided cores while their crossover lines being connected can be realized and the freedom of the core shape can be extended. As the magnetic material is not used near the teeth parts of the divided cores, it will be appreciated that the magnetic leakage between the teeth can be avoided and thus the efficiency can be increased. And furthermore, as a single unit is assembled in the coil winding frame with the insulation part, it will be appreciated that the easy assembly process can be established and that a small-sized and low-cost abduction-type motor can be realized.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.